The invention relates to a projection system comprising at least two light sources, a projection lens and at least a spatial light modulator located between the light sources and the projection lens, said light modulator comprising a plurality of light-deflection devices each provided with an element which is tiltable about a tilt axis, the tilt axes extending parallel to each other.
A spatial light modulator is understood to mean an analog or digital mirror device (such as TMA or DMD), as well as an eidophor whose reflective properties can be changed, and other light modulators with which the direction of a light beam can be changed.
In such a projection system, which is known from European patent application EP-A2-0 740 178, a spatial light modulator is illuminated by means of two light sources. The spatial light modulator comprises a plurality of light-deflection devices each provided with an element which is tiltable about a tilt axis. Each element is separately tiltable from a position directing light towards the projection lens to a position directing light away from the projection lens, and vice versa. A condenser lens directing the light from the light source to a first optical axis is associated with each light source. The projection system is further provided with a cylindrical lens which is located on the first optical axis, which lens receives the light from each condenser lens. The light subsequently passes through an exit condenser lens, whereafter it is directed onto the spatial light modulator.
A drawback of this known projection system is that the tilt directions of the individual elements of the spatial light modulator are not taken into account when positioning the light sources, so that there is a risk that no optimal light output is obtained.
It is an object of the invention to provide a projection system which may comprise a plurality of light sources, while an optimal light output is obtained.
This object is achieved in the projection system according to the invention in that the light sources are arranged with respect to the spatial light modulator in such a way that, in operation, the centers of the light beams coming from the light sources and projected on each element are located on a projection line which extends substantially parallel to the tilt axis of the element.
Since the light spots coming from the light source are located on a connection line extending parallel to the tilt axis, the light coming from all light sources will enter the element and will be deflected in the same direction when tilting an element.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.